We will use new techniques to explore the kinetics of axonal transport of specific substances in adrenergic and cholinergic nerves. First, in stop-flow experiments, migrating waves of endogenous material produced by cycles of local cooling and rewarming will be used to characterize the transport of aromatic 1-amino acid decarboxylase and choline acetyltransferase. This will complete our direct analysis of the behavior of the enzmes catalyzing biosynthesis of norepinephrine and acetylcholine. The relation between the subcellular distribution and the transport velocities of these enzymes will be examined with regard to the hypothesis that average velocity of transport is determined by the ease with which substances enter stationary regions of the axon. Second, experiments will be performed to determine the effects of subjecting nerves to small step-gradients of temperature arranged so that distal regions of nerve are supplied with graded increases in amounts of material transported from proximal regions. The consequent changes in local concentrations of dopamine-beta-hydroxylase activity will define the relation between the amount of material available for transport and the amount of material actually transported in adrenergic axons. The results may also provide clues as to whether axonal transport involves specific interactions between stationary particles and moving carriers or whether it involves non-specific flow of fluid and particles in microstreams of axoplasm. Third, we will study the origins of the large compartment of acetylcholinesterase that is stationary or slow moving and that can be selectively inhibited by echothiophate, a drug that is mainly excluded from nerve cells. By examining the recovery of this compartment from treatment with echothiophate, we expect to learn about the process of incorporation of acetylcholinesterase into surface membranes of mature axons and how this compares with incorporation during axonal development and regeneration.